This invention relates to the manufacture of artificial teeth for installation in metal or plastic base installed in the wearer's mouth. The teeth and the base constitute a denture which may include any number of teeth up to and including the entire upper or lower dentures or plates.
Currently, such artificial teeth are usually formed of one of two materials. Either they are of porcelain, which has been recognized as being too hard, or they are of a plastic material, which is too soft. Porcelain teeth are typically formed of molded porcelain. Since porcelain is quite brittle, in addition to being very hard, porcelain teeth are subject to mechanical failure from cracks. The other principal disadvantage of porcelain teeth is that, because of their hardness, they tend to wear or damage opposing natural dentition.
Plastic teeth have been more popular than porcelain because of the above disadvantages. But since they are softer, they tend to wear away rapidly. As they become worn, they no longer exert the normal force on the opposing natural dentition, permitting the natural teeth to move, and throwing off the patient's bite and function. Many efforts have been made to produce plastic materials which are harder and less susceptible to wear but none are comparable to natural dentition.
In recognition of the above problems, many workers have sought to employ various polyceramic mixtures and similar materials in an effort to provide a suitable denture material, which has hardness closer to natural dentition.
Patents describing composition intended for use in dental applications include:
U.S. Pat. No. 3,975,203 to Dietz
U.S. Pat. No. 4,131,597 to Bluethgen
U.S. Pat. No. 5,346,397 to Braiman
U.S. Pat. No. 5,447,967 to Tyszblat
U.S. Pat. No. 5,621,035 to Lyles
The above listed patents are merely exemplary of the many patents issued in this field.